01 - Combine the canned pumpkin purée with cinnamon, nutmeg, ginger, cloves, allspice, salt, and freshly ground black pepper in a small bowl. Mix until smooth and thoroughly blended.
02 - Arrange the bread slices on a clean surface. Evenly spread the prepared pumpkin mixture onto two of the bread slices. Layer the sliced cheddar and Gruyère (or mozzarella) cheese over the pumpkin mixture on these two slices.
03 - Place the remaining two bread slices on top of the cheese-layered slices to form two complete sandwiches. Ensure the fillings are enclosed.
04 - Generously spread the softened unsalted butter evenly over the outer surfaces of each sandwich. This will ensure a golden-brown crust when cooked.
05 - Preheat a large skillet or griddle over medium heat. Carefully place the buttered sandwiches onto the hot surface. Cook for approximately 3 to 4 minutes per side, pressing down gently with a spatula. Continue until the bread achieves a golden-brown color and the cheese is fully melted and gooey.
06 - Remove the grilled sandwiches from the skillet. Allow them to cool slightly before cutting them in half. If desired, use a cookie cutter to create festive Halloween shapes.